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When an Indian vaccine trial was halted midway, thousands of girls had had only one shot; following them for ten years showed one dose protected as well as three, changing the world's vaccination policy.
The study began as a randomised comparison of two versus three doses of quadrivalent HPV vaccine at nine Indian centres. Recruitment was suspended in 2010 by the government, leaving by-default cohorts of girls who had received one dose (4,949), two doses (4,980) or three doses (4,348). At a median follow-up of 9.0 years, vaccine efficacy against persistent HPV 16/18 infection was 95.4% (95% CI 85.0-99.9) after one dose, 93.1% (77.3-99.8) after two and 93.3% (77.5-99.7) after three, and one-dose antibody levels, though lower, were stable. With the KEN SHE randomised trial in Kenya, these results led WHO in 2022 to endorse one- or two-dose schedules, roughly halving the cost of protecting a girl.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
17,729 enrolled.
95% CI 85.0-99.9 · 95% CI 77.3-99.8 · 95% CI 77.5-99.7
Source| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Vaccine efficacy against persistent HPV 16/18 infectionprimary | One dose | 4,949 | 95.4% | - | - | link |
| Two doses | 4,980 | 93.1% | ||||
| Three doses | 4,348 | 93.3% |
One dose protects. WHO endorsed one- or two-dose schedules in 2022, halving the cost and the logistics of vaccinating girls, which is decisive for India (about 127,500 cervical cancers a year) and for the global elimination target. It also removed the main barrier to India's national programme with its home-made vaccine.
One trial page on OnCo cites this paper by its DOI; this record gives the citation a page of its own so a reader can follow it without leaving OnCo. Read the abstract above alongside the citing page listed under Related; the record was created automatically from the Europe PMC entry and its figures have not been checked by hand.
Shares CERVAVAC (quadrivalent HPV vaccine, India), Nonavalent HPV vaccine, Cancer prevention roadmap: tobacco control and vaccines → biomarker-guided chemoprevention → interception in carriers, Global access and affordability roadmap: essential medicines and generics → biosimilars and frugal trials → reliance, pooling and homegrown innovation.
Shares Rengaswamy Sankaranarayanan, Tata Memorial Centre, International Agency for Research on Cancer (IARC / WHO), Cancer prevention roadmap: tobacco control and vaccines → biomarker-guided chemoprevention → interception in carriers.
Shares International Agency for Research on Cancer (IARC / WHO), Cancer prevention roadmap: tobacco control and vaccines → biomarker-guided chemoprevention → interception in carriers, HPV & HBV vaccination, Prevention we already have is not deployed.
Shares International Agency for Research on Cancer (IARC / WHO), Cancer prevention roadmap: tobacco control and vaccines → biomarker-guided chemoprevention → interception in carriers, HPV & HBV vaccination, Prevention we already have is not deployed.
Shares Rengaswamy Sankaranarayanan, Tata Memorial Centre, International Agency for Research on Cancer (IARC / WHO), Prevention we already have is not deployed.
Shares KEN SHE (single-dose HPV vaccine), Nonavalent HPV vaccine, HPV & HBV vaccination, Prevention we already have is not deployed.
Shares Global access and affordability roadmap: essential medicines and generics → biosimilars and frugal trials → reliance, pooling and homegrown innovation, HPV & HBV vaccination, Prevention we already have is not deployed, Most of the world has almost no cancer care.
Shares Partha Basu, Single-dose HPV vaccination plus HPV self-sampling to reach WHO elimination in low-income countries, Rengaswamy Sankaranarayanan, Cancer prevention roadmap: tobacco control and vaccines → biomarker-guided chemoprevention → interception in carriers.